1. Field of the Invention
The present invention relates to a key actuating apparatus.
Priority is claimed on Japanese Patent Application No. 2007-077042, filed Mar. 23, 2007 and Japanese Patent Application No. 2008-061038, filed Mar. 11, 2008, the content of which is incorporated herein by reference.
2. Description of the Related Art
In general, a natural keyboard musical instrument such as an acoustic piano has a constitution in which, for example, a natural sound is generated by hitting a string with a rotationally movable hammer when a key is pushed. Such a natural keyboard musical instrument has an action mechanism between the key and the hammer. The action mechanism affects a special reacting force (braking force of the key) on a player via the key. In other words, the natural keyboard musical instrument has its own touch of the key because the instrument has an action mechanism.
On the other hand, a conventional electric keyboard musical instrument such as an electric keyboard which generates an electric sound has a mechanical portion such as a spring and a weight member for returning the key to its initial position. Moreover, the conventional electric keyboard musical instrument has a constitution in which, the player operates the key while acting against the reacting force of the spring, the weight member, and the like, upon pushing the key. Therefore, the touch of the key of the electric keyboard musical instrument is greatly different from the touch of the key of the natural keyboard musical instrument.
There is prior art (for example, see Patent Document 1 below) which has an object to obtain the same touch of a key as the natural keyboard musical instrument even by using an electric keyboard musical instrument. In the prior art, a key actuating apparatus and a control apparatus of the key actuating apparatus for applying a reacting force against a pushing force on the key by actuating the key are proposed. Moreover, in the prior art, a key actuating apparatus which is an electromagnetic actuator of a solenoid type is used.
With regard to the constitution of such prior art, for example, as shown in Patent Document 2 shown below, a plunger which constitutes the solenoid is connected to the key so as to change or adjust the reacting force. In such a case, the key has a rotation axis which is a fulcrum for a rotational motion, and is connected to the linearly movable plunger of the solenoid via a sliding mechanism which is constituted from multiple members (such as intermediate members and an axis). In other words, the sliding mechanism is an absorber of a difference or gap which is caused at a connection point between the rotationally-movable key and the linearly-movable plunger.    [Patent Document 1] Japanese Patent No. 3772491    [Patent Document 2] Japanese Patent No. 3191327
However, in a case such as shown in Patent Document 2 in which the plunger and the key are connected via the sliding mechanism constituted from multiple members, there is a possibility in which a backlash is caused among the multiple members. In such a case, it is hard to control a key-actuating operation by the control apparatus, and therefore, there is a problem of causing unnatural or uncomfortable touch of the key when a player pushes the key.